Pollen resources of two stingless bee species (Apidae: Meliponini) in disturbed tropical Andean forests: selectivity in generalist foraging

Abstract Stingless bees from Andean ecosystems exhibit selective foraging over a diverse array of floral resources. A few studies have examined how their selection of pollen resources changes with varying degrees of habitat disturbance in forest environments. The pollen species composition of honey and stored pollen pots from managed hives of Tetragonisca angustula and Melipona costaricensis was monthly recorded over 15 months. Hives were located in three vegetation covers: secondary forests, fallows, and crop fields. Additionally, pollen from corbicula loads was also sampled during three distinct periods. For both bee species, colonies located in crop fields yielded the fewest samples for palynological analysis and exhibited the lowest proportion of pollen from arboreal sources. Each bee species demonstrated differentiated pollen selection among the monthly available flowers. The highest abundance of palynomorphs selected by M. costaricensis came from nectar and pollen-producing tree genera, such as Miconia , Vochysia , Cupania , Clethra , and Myrcia , as well as the herb, Mimosa pudica . This contrasts with the selection made by T. angustula , which primarily derives from pollen-producing flowers of arboreal, shrubby, and herbaceous species, including Pourouma , Phyllanthus , Hedyosmum , Rhynchospora , and Scleria . Consistent selection for nectar- and pollen-rewarding tree flowers by M. costaricensis suggests a more specialized diet than T. angustula , indicating greater vulnerability of M. costaricensis colonies to small-scale forest ecosystem degradation.